To identify specific needs and possibilities for improved
mapping of land cover across boreal and temperate Northern Eurasia, we
compared the performance of recent land-cover products derived from
different sensors: MODIS (MODIS IGBP Land
Cover Collection 4 and 5), SPOT VEGETATION (GLC-2000) and
MERIS (GLOBCOVER)

What are the differences and similarities
between global datasets?

We examined the level of agreement among these data sets
across the entire region. On a qualitative level, the assessment of
general patterns indicates the highest degree of disagreement in
transitional zones at the northern and southern fringes of boreal
forest, in mountainous regions, and in areas of extensive wetlands,
agricultural development, and urban land use. The quantitative analysis
measured the level of disagreement between land-cover classes
aggregated according to dominant life form type of vegetation (trees,
shrubs, herbaceous, bare land, and permanent snow/ice).

What is the accuracy of global maps at NELDA test sites?

Validation of global datasets was performed with higher
resolution, Landsat-based land cover maps from
NELDA test sites. Fractional land cover was calculated for coarse
resolution pixel and used to construct fractional error matrices. Most
errors were associated with “mixed” coarse-resolution pixels (i.e.
those having nearly equal percentage of multiple class types), while
errors in “pure” (single class) pixels were low. In addition to actual
differences in land-cover classifications, other sources of discrepancy
among these land cover products include class definitions, map
projections, and spatial resolution.

Dominant Live Form Types

Differences in class definitions and legends between maps are a major difficulty for comparing global land cover data sets.
We converted each legend to a standard classification on the basis of the dominant live form types (LFT): tree, shrub, herbaceous and barren/sparse vegetation and water. Classes representing mixtures of vegetation types were labeled as 'mosaic'. Select a site on the left menu to compare LFT maps derived from global land cover datasets with Landsat-based reference maps.